I have been thinking about getting a Nikon Df, one of the factors being the reportedly excellent image quality possible. An alternative would be to get a high-end rangefinder, like the Contax G2. Ken Rockwell says that the lenses on the G2 are "far superior" to DLSR lenses:
The optics of the Contax G2 are equal or superior to Leica lenses, and far superior to Nikon or Canon lenses. Part of this is due to the Contax G2's design allowing rear lens elements to get closer to the film plane than in Leica, which allows lens designers more freedom to design better wide lenses, For example, the Contax G Zeiss 21mm f/2.8 has much less distortion than the LEICA ELMARIT-M 21mm f/2.8 ASPH, and both are much better than SLR lenses.
Is there some mechanical/physical reason why rangefinder lenses are better than DLSR lenses? Would I notice the (alleged) superiority in my photographs?